Fire did not spark human colonisation of cold Europe

Humans may have been much later to master fire than we thought. A review of supposed archaeological hearths in Europe suggests that the oldest date to just 400,000 years ago. The finding suggests that humans expanded into cold northern climates without the warmth of fire – and that cooking was not the evolutionary trigger that boosted our brain size.

Many of the “smoking guns” for prehistoric fire use – charred bone fragments or chunks of charcoal – do not necessarily imply that early humans could control fire. Our opportunistic ancestors may simply have exploited the occasional wild fires triggered by lightning, for example.

To try to pin down the earliest evidence of controlled fire use, Paola Villa at the University of Colorado in Boulder, and Wil Roebroeks at Leiden University in the Netherlands re-examined the data from over 100 European sites. They were looking for evidence of fires that were unlikely to have occurred naturally – those in caves, for example – and for clues that fire had been used in a controlled way. These include activities such as making pitch&colon; some early hominins made this sticky substance by burning birch bark and using it to glue pieces of flint to wooden handles to make stone tools easier to use.

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Bigger brains

The earliest European hearths date back between 300 and 400,000 years, the researchers conclude – much later than existing theories suggest. Some archaeologists think that controlled fire use dates back 1.6 million years. Richard Wrangham of Harvard University has even suggested that hominins began using fire 1.9 million years ago, leading to a cooking tradition that made digestion easier and freed up the extra energy our ancestors needed to grow bigger brains.

Although Villa and Roebroeks investigated only European sites, they think evidence of controlled fire use at a number of other sites is also up for debate. The Swartkrans site in South Africa is believed by some to contain 1.6 million-year-old evidence in the form of hundreds of charred bones. “But these might just have been sporadic natural fires that were taken advantage of,” says Villa. In fact, just one site earlier than the 400,000 year mark has strong evidence of controlled fire use, the pair says&colon; the 780,000-year-old Gesher Benot Ya’aqov site in Israel.

Freezing in Europe

“The European evidence strongly suggests that the habitual and controlled use of fire was a late phenomenon,” Villa and Roebroeks conclude.

The findings controversially suggest that people migrated from Africa to the below-freezing winter temperatures of Europe without fire. These early hominins might have combined a high-protein diet with a highly active lifestyle to survive, the researchers speculate.

The conclusion also questions Wrangham’s hypothesis that an increase in human brain size was tied to the invention of cooking.

Wrangham remains to be convinced. He points out that whenever cooking did arise, it would have led to profound biological effects on the humans alive at the time. There’s no evidence for those effects in 400,000-year-old hominin fossils, he says.